Wheelchair lifts of the type installed in the stairwells of transit vehicles, such as city buses, are well-known. One type of wheelchair lift commonly referred to as a "step lift," is illustrated in U.S. Pat. No. 4,466,771 to Thorley et al. (the '771 patent). Another type of wheelchair lift, commonly referred to as a "platform lift, " is illustrated in U.S. Pat. No. 4,058,228 to Hall (the '228 patent).
Both wheelchair step lifts and platform lifts typically include a wheelchair platform that is movable from a lowered position in which the wheelchair platform lies adjacent the sidewalk or ground to a raised position in which the wheelchair platform lies in the same plane as the aisle way of the bus, train, or other vehicle on which the lift is mounted. A wheelchair is loaded onto the wheelchair platform when it is in the lowered or raised position at which time the platform is moved to the opposite position in order to allow the wheelchair to be moved into or out of the bus or other vehicle on which the wheelchair lift is mounted. In order to decrease storage space and improve usability, a number of platform-type wheelchair lifts such as that described in the '228 patent include wheelchair platforms that retract under the bottom of the bus or other vehicle on which the lift is mounted. In some wheelchair lifts such as that disclosed in the '228 patent the wheelchair platform forms the lower step of the vehicle entryway.
A number of wheelchair lifts incorporate outer and sometimes inner (with respect to the vehicle) foldable barriers that help to maintain a wheelchair on the wheelchair platform. In addition, some wheelchair lifts include fixed side barriers to help maintain the wheelchair on the wheelchair platform. It would be beneficial if improved outer, side and inner barriers could be developed to ensure that a wheelchair cannot move off the wheelchair platform during operation of the wheelchair lift. It would also be beneficial to improve current wheelchair barriers to improve their capability to absorb energy from an impact between a wheelchair and the barriers, to help reduce the possibility of injury to the wheelchair occupant, as well as reduce the high loads applied to the mechanisms as a result of impact. It would also be beneficial to provide both electrical and mechanical mechanisms that prevent the barriers and lift from operating improperly.
The present invention is a wheelchair lift that overcomes some of the disadvantages of prior art wheelchair lifts.